Non-volatile memory (NVM) storage is very popular in the computer industry and the electronics industry. Computers have long utilized NVM storage for basic input/output system (BIOS) code storage and other important boot routines. But, more recently, the usage models for NVM storage have expanded greatly from digital camera image storage to digital music player storage of songs. NVM devices have dramatically decreased in size and increased in storage capacity. Now the computer industry is beginning to build solid state drives (SSDs) utilizing NVM devices for mass storage. SSDs may someday completely replace conventional hard disk drives due to in part to superior performance, smaller profiles, and lower power requirements.
One long known detriment to NVM devices has been their finite lifespan. Unlike their volatile memory counterparts, the circuitry within NVM devices deteriorate over time. Due to this deterioration, the reference voltage required to effectively read NVM devices may change over time. Additionally, data stored within NVM devices may degrade after some data retention time. Although this aging characteristic of NVM devices does not happen at nearly the rate it does for volatile memory, data retention is still a factor when using NVM.